[M3devel] symlink grief?

[Jay K]

No they were in a very central place m3-libs/libm3/src/os/POSIX/FSPosix.m3.
How about:


PROCEDURE CStatus(s: Ctypes.char_star; VAR status: File.Status): INTEGER =
  VAR statBuf: Ustat.struct_stat;
  BEGIN
    IF Ustat.stat(s, ADR(statBuf)) < 0 AND Ustat.lstat(s, ADR(statBuf)) < 0 THEN
      RETURN -1;
    END;
    status.type := FilePosix.FileTypeFromStatbuf(statBuf);
    (* Could make following assignments conditional on type: *)
    status.modificationTime := FLOAT(statBuf.st_mtime, LONGREAL);
    status.size := statBuf.st_size;
    IF status.size < 0L THEN RETURN -1 END;
    RETURN 0
  END CStatus;


I can look again, *maybe* rmrec can avoid calling here.
Though probably the best way to achieve that is by writing two independent versions in C.
I think the Modula-3 file system libraries are just too keen on calling stat, which fails
for dangling symlinks.

 - Jay

----------------------------------------
> Date: Fri, 3 Sep 2010 13:10:51 +0200
> From: wagner at elegosoft.com
> To: m3devel at elegosoft.com
> Subject: Re: [M3devel] symlink grief?
>
> Symbolic links usually `just work'.
> If you have changed stat to lstat for all use cases, that will of
> course cause problems. I thought your changes were local to the
> rmrec implementation for quake. Aren't they?
>
> If not, it will be better to revert them.
>
> Olaf
>
> PS: Windows NTFS does support symbolic links, too, though I've probably
> never used them: http://en.wikipedia.org/wiki/NTFS_symbolic_link
>
> Quoting Jay K :
>
> >  +++ /cm3/bin/cm3  -ship -DROOT=/home/jay/dev2/cm3 +++
> > --- shipping from I386_LINUX ---
> >
> > "/home/jay/dev2/cm3/m3-libs/m3core/I386_LINUX/.M3SHIP", line 1:
> > quake runtime error: unable to create directory "/cm3": errno=17
> >
> > --procedure--  -line-  -file---
> > make_dir           --  
> >                     1  /home/jay/dev2/cm3/m3-libs/m3core/I386_LINUX/.M3SHIP
> >
> > Fatal Error: package build failed
> >  *** execution of [,
> > 
> >
> >
> > /cm3 is a symlink to /home/jay/cm3
> > They both exist.
> > /home/jay/cm3 is a directory.
> >
> > I predict no good answers here.
> >  - a code base that historically used stat, that I changed to lstat.
> >
> > I think maybe I should put it back to stat.
> > And maybe come up with new functions for fs_rmrec to use.
> >
> > Wild guess... we have code like:
> >
> >
> > PROCEDURE IsDirectory (path: TEXT): BOOLEAN =
> >   VAR s: File.Status;
> >   BEGIN
> >     TRY
> >       s := FS.Status (path);
> >       RETURN (s.type = FS.DirectoryFileType);
> >     EXCEPT OSError.E =>
> >       RETURN FALSE;
> >     END;
> >   END IsDirectory;
> >
> >
> > Maybe the right thing is to mimic Posix and allow code like:
> >
> >
> > PROCEDURE IsDirectory (path: TEXT): BOOLEAN =
> >   VAR s: File.Status;
> >   BEGIN
> >     TRY
> >       s := FS.LinkStatus (path);
> >       RETURN (s.type = FS.SymblicLinkFileType);
> >     EXCEPT OSError.E =>
> >       RETURN FALSE;
> >     END;
> >   END IsDirectory;
> >
> > or such?
> >
> > Not sure it is needed.
> >
> > Or FS.StatusNoLinkResolve? Is that clearer?
> >
> > There are a few basic problems here:
> >   - The "Modula-3 code base" has been written I assume without
> > symlinks in mind. ??
> >   - I don't have symlinks in mind, much at all, since I'm usually
> > not on a system with them.
> >   I don't have a mental model of how to program with them, etc.
> >   Maybe some short document I can read and memorize?
> >
> >
> >  - Jay
> >
>
>
>
> --
> Olaf Wagner -- elego Software Solutions GmbH
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